Shockproof x-ray unit



Sept. 6, 1938. c. M. sLAcK 2,129,387

sHocKPRooF X-RAY 'UNIT I Filed ooi. 51, 1954 2 sheets-sheet 1 IllaaaaATTORNEY 4.

Sept. 6, 1938.

c. M. sLAcK SHOGKPROOF X-RAY UNIT Filed oct. 51, 1954 ,2 sheets-sheet 2Nw ww. mw m R n n nw ww mw NN R R R N R A ww N www LPatented Sept. 6,1938 UNITED STATES PATENT OFFICE SHOCKPROOF X-RAY UNIT ApplicationOctober 31, 1934, Serial No. 750,760

3 Claims.

My invention relates to X-ray apparatus and s has particular referenceto shockproof X-ray ap- A paratus wherein the danger of accidentalshocks resulting to a patient or operator are entirely eliminated.

In the prior art the most common type of such apparatus is that oftheso-called oil immersed type wherein the X-ray tube and the high tensiontransformer are immersed in a cooling and insulating material andencased in a metallic casing. However, a unit of this type has severaldisadvantageous features among which are its weight, which makes it veryunwieldy to manipulate and as the tube is immersed in oil the latter4clt's as a filter for the X-rays emanating from the A further type ofshockproof unit which obviates the objectionable features inherent inthe oil immersed type is that knownV as the cable connected unit. I'hislatter type consists of a metallic housing lfor the X-ray tube and theenergy for operating the tube is supplied from a suitable source throughgrounded metallic sheathed cables. The cables are suitably secured tothe metallic casing through the intermediary of appropriate connectingbushings to effectively ground the metallic housing. I'he midpoint ofthe high tension transformer, which latter normally is employed for thesource of energy, is usually grounded thus requiring insulation betweenthe electrode terminals of the tube and the metallic casing suil'icientto prevent spark-over at a voltage equal to one-half the maximum voltageof the source.

Because the tube in this cable connected shockproof unit operates in airit is of larger size for the same applied voltage as when operating inoil. However, the tube size may be reduced somewhat below that normallyrequired for a tube operating in air by the provision of suitableinsulation between the tube terminals and the grounded metallic casing.

Heretofore it has been customary to provide blocks or sleeves ofinsulating material between the cable bushings and the tube terminalswhich are in turn provided with suitable terminals for connecting therespective conductors of the cables to the electrode terminals of thetube. This construction is not only costly to manufacture and assemblebut in addition forms numerous leakage paths between the high tensioncarrying parts and grounded metallic casing where corona very readilyforms during operation of the tube as well as frequent spark-over due todeterioration of the insulating material by the corona effect.

It is accordingly an object of my present inven- (Cl. Z50-34) tion toprovide a shockproof X-ray unit wherein the X-ray tube is of aforeshortened length than normally required for a tube operating in airat the same applied voltage and the electrical energy for energizing thesame is supplied through grounded metallic sheathed cables which enterthe ray proof housing and are so connected to the terminals of the X-raytube as to reduce the spacing normally required between the tubeterminals and the grounded casing.

Another object of my present invention is the provision of a cableconnected shockproof unit wherein the high tension carrying cables areso connected to the metallic ray-proof housing as to effectively groundthe same and are connected to the terminals of the tube in such manneras to conceal all high tension carrying parts whereby sparkover and theformation of corona is eliminated resulting in the utilization of anX-ray tube of smaller dimensions than that normally required for a tubeoperating in air at the same applied voltage.

Another object of my present invention is the provision of a shockproofX-ray unit wherein the high potential energy for the tube -is suppliedby grounded metallic sheathed cables connected to the ray-proof metallichousing and the X-ray tube terminals in such manner as to ground thehousing and form a support for the tube as well as sufficiently insulatethe tube terminals so that the actual air gap spacing between the latterand the grounded housing may be reduced resulting in the utilization ofa tube of foreshortened length for the same applied voltage as normallyrequired when operating inair.

Another object of my present invention is the provision of a shock-proofX-ray unit wherein the overall length of the tube is considerablyreduced below that normally required for a tube operating in air at thesame applied voltage and provided with reentrant stems having theelectrode terminals recessed therein and the high tension cables forsupplying the energy for the tube are connected directly to the recessedelectrode terminals to form the requisite insulation to pre-` ventspark-over and the formation of corona between these terminals and thesurrounding grounded ray-proof housing.

A further object of my present invention is the provision of an X-raytube of foreshortened length provided with reentrant stems and havingits respective electrode terminals recessed therein a sufcient distanceto prevent spark-over therebetween at the maximum operating voltage ofthe tube.

Still further objects of my present invention will become obvious tothose skilled in the art by reference to the accompanying drawingswhere- Figure 1 is a side View, partly broken away, of a shockproofX-ray unit constructed in accordance with my present invention,

Fig. 2 is a sectional View taken on the line II--II of Fig. 1,

Fig. 3 is a sectional View taken on the line III- III of Fig. 1,

Fig. 4 is a sectional View taken on the line IV IV of Fig. 1,

Fig. 5 is a side view in cross section and on an enlarged scale of theunit shown in Fig. l, and

Fig. 6 is a sectional fragmentary view on a still larger scale of theunit as shown in Fig. 5.

Referring now to the drawings in detail I have shown in Fig. l an X-raytube comprising an elongated evacuated vitreous envelope 5 which issurrounded by a metallic or other suitable ray opaque housing 6 forpreventing the egress of X-rays except through a Window 1 provided rinthe housing. The envelope is provided with reentrant stems 8 and 9extending well into the envelope, as can be more readily seen in Fig. 5,with the innermost portion of the stem 8 being formed into a press Illthrough which a pair of conductors II pass to the cathode electrodeshown generally at I2. This latter electrode comprises the usualfilament I3 which is recessed Within a focusing cup or shield I4, inturn fitting over the press portion I0 of the reentrant stem 3, andsecured in place by means of a metallic ring or the like `I5. Aninsulated disc I6 is suitably secured to the .inner periphery of thereentrant stem il at the inner extremity thereof and is provided with apair of recessed metallic sleeves l1 and I 9 which are connected to thefilament I3 by the conductors II passing through the press and thusconstitutes the cathode terminal for the tube.

An anode electrode I9 formed of a material of good electrical andthermal conductivity, such as copper or the like, and provided with theusual target 20 of refractory metal, is sealed by a feather edged copperannulus ZI to the reentrant stem portion 9 of the envelope 5. A vitreousglass sleeve 22 fused to the envelope is disposedinteriorly thereof andextends longitudinally from Well in back of the point of seal of theanode and the envelope to considerably beyond the press I6 formed in thereentrant stem 8. This sleeve is provided with constrictions 23 adjacentthe anode and cathode but as the construction and operation of the sameforms the basis of my copending application Serial No. 750,633, filedOctober 30, 1934, and forms no part per se of my present inventionfurther detailed description herein is deemed unnecessary.

The anode I9 is provided with a longitudinal recess 24 (Fig. 6) threadedat the outer end adjacent the reentrant stem 9 and is arranged to beengaged by a metallicI member 25 provided with a recess 26 whichtogether form an anode terminal similar to the cathode terminalcomprising the disc I6 with its recessed sleeves I1 and I8. In order tocirculate a cooling and insulating medium through the anode, such forexample as oil, to cool the same during operation of the tube the member25 is further provided with a metallic conduit 21 threadedly engagingVthe same and extending Well into the recess 24, and this conduitregisters with a radially extending passageway or bore 28 formed thereinand made fluid tight by means of aplug 29.

A suitable tting in the form of an elbow of insulating material 30 alsothreadedly engages the member 25 and forms a passageway communicatingwith the bore 28. An inlet conduit 3I also of suitable insulatingmaterial extends from an appropriate reservoir (not shown) which in turnengages the elbow thus forming a continuous inlet passage from thereservoir to the interior of the anode with the insulationcharacteristic of the oil being augmented by the insulated elbow 39 andthe conduit 3I so that the potential applied to the anode will not betransmitted to other parts of the unit by the cooling system.

The conduit 21 is of slightly less diameter than the recess 24 providedin the member 25 for a portion of its length and thus forms an annularpassageway 32 communicating with the interior of the hollow anode recess24. An angularly disposed passageway 33 in the member 25 communicateswith the annular passage 32 and an elbow 34, similar to the elbow 30,threadedly engages the member 25 concentric With the passageway 33, saidelbow being in turn engaged by an insulated return or outlet conduitleading back to the reservoir.

Accordingly during operation of the tube the cooling fluid flows fromthe reservoir through the inlet conduit 3l, elbow 30, passageway 28 andconduit 21 to the interior of the anode immediately in back of thetarget. The cool fluidafter striking the heated parts of the anode thenflows through the passageways 24, 32, and 33, respectively, and thenceby means of the elbow 34 and outlet conduit35 back to the reservoir.over, due to the insulating material itself and the utilization ofinsulated conduits no potential stress is impressed between any otherportions of the apparatus and the circulatory cooling system.

The respective ends of the envelope of the tube have insulated caps 36and 31 secured thereto in any suitable manner, such for example ascement 38. In order to support the tube, as Well as supply highpotential energy thereto from a suitable source, such as a high voltagetransformer (not shown) having the midpoint of its secondary windinggrounded,`a pair 'of grounded metallic sheathed cables 39 and 40 extendfrom the source to the tube. Thesecables have the metallic sheathingremoved therefrom a distance corresponding to that from the outsidesurface of Vthe respective end caps 36 and 31 and the cathode and anodeterminals which latter are, as before stated, disposed at the innermostextremities of the respective reentrant stems 8 and` 9. A sleeve ofinsulating material 4I snugly fits the unsheathed portions of therespective cables and accordingly forms an integral part thereof. Thesleeve 4I forming a part of 'the cable 39 is provided with a pair ofpins 42 slidably engaging the recessed sleeves I1 and I8 ofthe cathodeterminal with these pins being connected to the conductors of the cable39 for the purpose of supplying cathode heating current as well as oneside of the high potential energy to the cathode, and the oable'39 isheld in position by a flange portion 43 of the sleeve 4I which engagesthe end cap 36 in any suitable manner, such as by set screws 44, thussupporting one end of the tube 5 directly upon the cable 39.

Similarly the insulating sleeve 4I, which forms an integral part of thecable is likewise provided with a pin 45, electrically connected totheconductor in the cable 4D, said pin slidably engaging the recess 26provided in the member More- 25 and constituting the anode terminal'.This cable dsupports the anode end of the tube in. the same manner asthe cathode'end is supported by the cable 39, namely, by having Ytheflange portion of its insulating sleeve 4| secured to the end cap 31.

Accordingly the cables 39 and 49 extend directly into the reentrantstems 8 and 9, respectively, and the conductors .of these 'cables arenot only connected directly to the electrode terminals disposedinteriorly of these reentrant stems, but the tube itself is supporteddirectly by the cables due to their integral sleeves 6| being .connectedto the respective end caps 3B and 31.

Inasmuch'as these grounded high tension cables directly enter thereentrant stems and are connected to the respective recessed electrodeterminals they not only conceal all high tension carrying parts but inaddition form suicient insulation enabling the spacing between thegrounded sheathing of the cables 39 and 49 as well as the metalliccasing 6 to be materially reduced for a tube normally operating in airat the same applied voltage. Moreover, a single leakage path is formedalong which the current would have to travel to cause a spark-over,namely, between the respective electrode terminals along the integralcable sleeves 4l to the grounded sheathing or casing but, despite thefact the actual air gap spacing therebetween is materially reduced asjust stated, this path is more than suiicient to prevent spark-over orthe formation of corona tending to cause deterioration of theinsulation. By enabling the spacing between all high tension carryingparts and ground to be materially reduced it naturally follows that theoverall size of the entire unit is likewise reduced thus forming a morecompact unit which may be manipulated about a patient with greaterfacility and is more economical to manufacture.

The metallic housing 6 surrounds the tube 5 and in order to render itray pervious except at the window 1 the same may be provided with alayer of metal 46, of high atomic weight such as lead or the like. Eachend of the casing is supported by the respective end caps 36 and 31 ofthe tube. For the purpose of completing a metallic connection for themetallic housing to the grounded metallic sheathing of the cables 39 and40, a metallic collar 41 threadedly engages each end of the housing and.is provided with a portion 48 having a plurality of slots 49 extendinglongitudinally to form a good frictional contact with the metallicsheathing of the respective cables and yet allow a slight flexibilitythereof.

It thus becomes obvious to those skilled in the art that I have provideda shockproof X-ray unit wherein the possibility of accidental shocksresulting to a patient or operator are entirely eliminated. The highpotential energy for the tube is supplied through grounded metallicsheathed cables which are directly connected to recessed electrodeterminals of the tube in such a manner that not only are all hightension carrying parts concealed but, in addition the insulation formedby the cables themselves is such as to reduce the Although I have shownand described one specific embodiment of my invention I do notfdesire tobe limited thereto as various other modifications of the same may bemade without departing -from the spirit and'scope of theappended claims.

:housing having an envelope` of shorter length thanv that normallyrequired for a tube operating in air at the same applied voltage andprovided with oppositely disposed reentrant stems extending asubstantial distance longitudinally of said envelope, electrodeterminals disposed at the innermost extremity `of said reentrant stems,and meansfor supporting said tube and for supply' ing electrical energythereto comprising grounded metallic sheathedv cables having themetallic sheathing thereof connected to said metallic housing andprovided with an unsheathed portion, an insulated sleeve snugly ttingthe unsheathed portion of said cables and extending directly into saidreentrant stems to form a single leakage path and to increase theair-gap spacing between said electrode terminals and all groundedmetallic parts to prevent the formation of corona during operation ofsaid tube, said insulated sleeve being connected to said X-ray tube andsaid housing to form a support therefor, and said insulated sleeveshaving terminals connected to said cables and slidably engaging theelectrode terminals disposed at the innermost extremity of saidreentrant stems.

2. A shockproof X-ray apparatus comprising an X-ray tube having anenvelope of shorter length than that normally required for ar tubeoperating in air at the same applied voltage and provided withoppositely disposed hollow reentrant stems extending a substantialdistance longitudinally of said envelope, electrode terminals disposedat the innermost extremity of said reentrant stems, a metallic X-rayopaque housing supported by said tube and spaced relative to saidelectrode terminals a distance which is normally insufficient to preventspark-over or the formation of corona therebetween during operation ofsaid tube, grounded metallic sheathed cables for supplying electricalenergy to said X-ray tube and for supporting said tube and housing as aunit, said cables having the metallic sheathing thereof connected tosaid housing to ground the latter and provided with an unsheathedportion, an insulating sleeve snugly fitting the unsheathed portion ofsaid cables and extending directly into said reentrant stems to form asingle lleakage path and to increase the air-gapspacing between saidelectrode terminals and all grounded metallic parts to prevent theformation of corona during operation of said tube, said insulatingsleeve being provided with a flange portion secured to said tube andcontacting said housing whereby said X-ray tube and housing aresupported as a unit by said cables, and said insulated sleeves havingterminals connected to said cables and slidably engaging the electrodeterminals disposed at the innermost extremity of said reentrant stems.

3. A shockproof X-ray apparatus comprising an X-ray tube having anenvelope of shorter length than that normally required for a tubeoperating in air at the same applied voltage and provided withoppositely disposed hollow cylindrical reentrant `stems extending asubstantial distance longitudinally of said envelope, an X-ray opaquehousing surrounding said X-ray tube and in Vcontact-,with aportionziofsaiditube to x the position thereof within-saidhousing andprovided `.with an X-ray pervio-us windowvrinrsaid housing in lalignmentwith the ray projecting portion of said 'X-'ray tube, electrodeterminals disposed at the innermost extremity of said reentrant stems`and spacedfrom said housing a distance normally insufcient `to preventspark-over therebetween `at the operating voltage of said tube, groundedmetallic sheathed cables for supplying electrical energy to said X-raytube and having an unsheathed portio-n, a metallic iiange carried by themetallic sheathed portion of said cables and connected .to said housingto ground the latter, an insulating sleeve snugly fitting the unsheathedl portion of said cablesand extending directly into said reentrant stemsto form a single lleakage path Vand to increase the air-gap spacingbetween said electrode terminals and all grounded metallic parts toprevent spark-over or the formation I;

Vreentrant stems.

vClif-IARI'JES MORSE SLACK.

